1. Technical Field
The present invention relates generally to an optical fiber amplifier, and in particular, to an L-band optical fiber amplifier using amplification of an optical fiber doped with a rare-earth element.
2. Related Art
Wavelength division multiplex (WDM) transmission is an information transmission scheme using optical fibers in which the wavelength area of an optical fiber is separated into a plurality of channels, the channels are multiplexed, and thus signals at different wavelengths are transmitted through the optical fiber at the same time, to thereby increase information transmission capacity.
A plurality of optical amplifiers are used between a transmitter and a receiver in a wavelength division multiplex transmission system to compensate for signal attenuation resulting from long distance transmission. The efficiency of optical amplifiers is important for transmission of optical signals.
I have found that it would be desirable to increase optical amplification efficiency. Efforts have been made to improve optical amplification.
Exemplars of recent efforts in the art include U.S. Pat. No. 5,815,309 for An Optical a Amplifier and Process for Amplifying an Optical Signal Propagating in a Fiber Optic issued to Lawrence et al., U.S. Pat. No. 5,652,763 for A Mode Locked Laser Diode in a High Power Solid State Regenerative Amplifier and Mount Mechanism issued to Delfyett, Jr., U.S. Pat. No. 5,790,303 for A System for Amplifying an Optical Pulse Using a Diode-Pumped, Q-switched, Intracavity-Doubled Laser to Pump an Optical Amplifier issued to Weston et al., U.S. Pat. No. 5,530,582 for A Fiber Source For Seeding an Ultrashort Optical Pulse Amplifier issued to Clark, U.S. Pat. No. 5,861,973 for An Optical Amplifier for Collectively Amplifying Optical Signals Having a Plurality of Multiplexed Wavelengths issued to Inagaki et al., U.S. Pat. No. 5,963,363 for A System and Method for Amplifying an Optical Pulse and Pumping Laser Therefor issued to Weston et al., U.S. Pat. No. 5,568,309 for A System andMethodforAmplification and Wavefront Compensation of Depolarized Optical Beams issued to Rockwell, U.S. Pat. No. 5,689,595 for A Rare Earth-doped Fiber Amplifier Assemblies for Fiberoptic Networks issued to Pan, and U.S. Pat. No. 5,136,420 for An Optical Fibre Amplifier issued to Inagaki et al.
While these recent efforts provide advantages,I note that they fail to adequately provide an L-band (long band) optical amplifier using seed beam increasing L-band amplification efficiency.
It is, therefore, an object of the present invention to provide an L-band optical fiber amplifier with increased L-band amplification efficiency.
It is another object of the present invention to provide an L-band optical fiber amplifier with improved gain flatness with respect to wavelengths of signal light when the length of an optical fiber and the intensities of input signal light and pumping light.
The above objects and others are achieved by providing an L-band optical fiber amplifier. The L-band optical fiber amplifier includes an optical fiber doped with a rare-earth element, at least one pumping light source for emitting pumping light to the optical fiber, a seed beam source for emitting a seed beam at a predetermined wavelength band, and a seed beam coupler disposed between an input terminal and the optical fiber, for coupling input signal light with the seed beam and feeding the coupled light forward to the optical fiber.
To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides an L-band optical fiber amplifier apparatus, comprising: an optical fiber being doped with a rare-earth element; at least one pumping light source emitting pumping light to said optical fiber; a seed beam source emitting a seed beam at a predetermined wavelength band; and a seed beam coupler being disposed between an input terminal and said optical fiber, coupling an input optical signal with the seed beam and feeding the coupled light forward to said optical fiber.
To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides an L-band optical fiber amplifier apparatus, comprising: an optical fiber being doped with a rare-earth element; at least one pumping light source emitting pumping light to said optical fiber; a seed beam source emitting a seed beam at a predetermined wavelength band; and a seed beam coupler being disposed between an output terminal and said optical fiber, coupling an input optical signal with the seed beam and feeding the coupled light reversely to said optical fiber.
To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides an apparatus, comprising: an optical fiber; at least one pumping light source emitting pumping light to said optical fiber; a seed beam source emitting a seed beam; and a seed beam coupler coupling an input optical signal with the seed beam and feeding the coupled light to said optical fiber.
The present invention is more specifically described in the following paragraphs by reference to the drawings attached only by way of example. Other advantages and features will become apparent from the following description and from the claims.